<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>float_example</title>
    <style>
        *{
            margin: 0;
            padding: 0;
        }
        /*.per{*/
            /*width:500px;*/
            /*height: auto;*/
            /*border: 1px solid #000;*/
            /*overflow: hidden;*/
            /*zoom: 1;*/
        /*}*/
        .per{
            width:500px;
            height: auto;
            border: 1px solid #000;
            float: left;
        }
        .test{
            width: 80px;
            height: 30px;
            background-color:red;
            border: 1px solid #ffffff;
            float: left;
        }
        .bro{
            width: 100px;
            height: 100px;
            background-color:blue;
            clear: both;
        }
    </style>
</head>
<body>
<div class="per">
    <div class="test"></div>
    <div class="test"></div>
    <div class="test"></div>
</div>
<div class="bro"></div>
</body>
</html>